Question 10 Elemental sulfur can be used to control outbreaks of powdery mildew on grapes - VCE - SSCE Chemistry - Question 10 - 2009 - Paper 1

To find the concentration of barium ions remaining in the sample solution, we first refer to the calibration curve using the absorbance of the solution.

Given that the absorbance measured is 0.11, we correlate this value with the linear relationship defined by the standard solutions:

1. Locate the absorbance of 0.11 on the Y-axis of the calibration curve.
2. Draw a horizontal line from this point until it intersects with the calibration curve.
3. From the intersection, draw a vertical line down to the X-axis to read the corresponding concentration of barium ions.

Assuming the graph shows a concentration of approximately 21 mg/L: The concentration ($C_{Ba}$) in the 10.00 mL sample solution is 21 mg/L.

Next, to find the mass of barium ions remaining:

Using the formula:

$ext{Mass} = ext{Concentration} imes ext{Volume}$

we convert the volume from mL to L:

$ext{Volume} = 10.00 mL = 0.010 L$

Then calculate:

$ext{Mass} = 21 ext{ mg/L} imes 0.010 ext{ L} = 0.21 ext{ mg}$